1. Field of the Invention
The present invention concerns firstly a method for determining the transmittance of a filter circuit adapted to transform the impulse response of a filter into a minimal phase response and secondly a filter implementing this method.
2. Description of the Prior Art
A response is a minimal phase response if its z transform has zeros only within the unity circle in the complex plane.
In methods used until now there has been either a systematic search for all the zeros of the transfer function associated with the impulse response to be transformed followed by extraction of those whose modulus is greater than or equal to 1 or a search for only those zeros whose modulus is greater than or equal to 1 as disclosed in the article "Adaptive adjustment of receiver for distorted digital signals" IEE Proc. Part F (August 1984) Vol 131, pages 526 to 536.
These methods are of limited accuracy, however, and their complexity increases in proportion to the length of the filter. The number of operations to be performed is also a random variable and the convergence time varies.
An object of the invention is to remedy these problems by proposing a method for determining transmittance of a filter circuit associated with a filter having an impulse response H(z), the filter circuit being designed so that the global impulse response G(z) of the filter and the filter circuit is a minimal phase response, this method having a fixed convergence time and being of reduced complexity.